A.A. Mane

Superior selectivity and enhanced response characteristics of palladium sensitized vanadium pentoxide nanorods for detection of nitrogen dioxide gas

Vanadium pentoxide (V2O5) nanorods have been deposited onto the glass substrates by spraying 75ml of 30mM vanadium trichloride (VCl3) solution at optimized substrate temperature of 400°C. The XRD study confirms the formation of orthorhombic crystal structure of V2O5 nanorods. The FE-SEM micrograph shows the nanorods-like morphology of V2O5. The presence of palladium (Pd) in the Pd-sensitized V2O5 nanorods is confirmed using EDAX study. The gas sensing measurements show that the Pd-sensitized V2O5 sensing material is an outstanding candidate for nitrogen dioxide (NO2) gas detection. Obtained results demonstrate that the Pd-sensitized V2O5 nanorods show the superior selectivity for NO2 gas in comparison with other gases such as NH3, H2S, CO, CO2 and SO2 at an operating temperature of 200°C. It shows the 75% response for 100ppm NO2 gas concentration with response and recovery times of 22s and 126s, respectively. Finally, the gas sensing mechanism based on chemisorption process is proposed to illustrate how Pd nanoparticles affect the gas sensing characteristics (response and response-recovery times).

Template-free TiO2 photoanodes for dye-sensitized solar cell via modified chemical route

Surfactant and template-free Titanium dioxide (TiO2) spheres have been deposited via ultrasonic rinsing assisted modified successive ionic layer adsorption and reaction (M-SILAR) method. The effect of M-SILAR cycle variation on the growth of TiO2 films and power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs) has been reported. Also, the significant influence of the dye adsorption time of photoelectrodes on the overall PCE of TiO2 based DSSCs has been investigated systematically. The SEM images reveal that the TiO2 microspheres are made up of densely packed and interconnected nanospheres. After dye loading maximum absorption peak around 500nm is seen with broader coverage in the visible region of the solar spectrum. The excess amount of dye for dye loading time 15h did not contribute to current and is suspected to be present either in multilayers or physisorbed on the surface of TiO2. The DSSC prepared using photoelectrode TO125 and dye loading time of 12h exhibited the highest power conversion efficiency (PCE) of 1.16% with short-circuit current density (Jsc) of 8.17mA/cm2, open circuit voltage (Voc) of 0.42V and fill factor of 0.34. The PCE is attributed to the large molecular interconnected TiO2 spheres diffusing visible light to enhance the light absorption. Also, it possesses relatively superior 3-D microsphere like structure and thus provides the effective pathway to the photogenerated electrons with low recombination rate, leading to attaining the high PCE.